This invention relates to a grinding machine for grinding the end faces of a coil spring as a workpiece.
The conventional grinding machine of this type includes, for example, one having a construction wherein the lower end portion of each of plural coil springs is inserted into each of those plural holes for holding the coil springs in place which are formed in the base plate; and in a state wherein each coil spring is vertically held in place a grinding wheel is pressed against the upper end face of each coil spring, thereby to perform grinding. In this type of grinding machine, the number of coil springs ground per unit time depends upon the grinding area of the grinding wheel, namely, upon the wheel diameter, failing to grind so large a number of coil springs. If the grinding ability is forcibly improved, the wheel diameter will be enlarged to an extreme extent, which renders the machine bulky and simultaneously increases the possibility of wheel breakage occurring during the wheel rotation. Further, since, in this type of grinding machine, the diameter of the spring retaining hole is so specified as to conform with a specific spring diameter, there is the inconvenience that it is impossible to grind coil springs whose diameters are different from the specific spring diameter.
The conventional grinding machine also includes one constructed such that coil spring retaining jigs, respectively, specified for each diameter of various coil springs are respectively set on the base plate of the machine, thereby to retain each coil spring on the base plate via each jig. However, in this construction, the jig replacement should be performed each time the spring diameter is varied, which makes the replacement operation troublesome, failing to attain high operational efficiency.